1. Field of the Invention
The invention herein refers to a vehicle air bag and more particularly to a passenger's side vehicle air bag adapted to deploy in a controlled manner.
2. Prior Art
Many modern vehicles incorporate one or more inflatable air bags for the protection of occupants in the event of a crash. The air bags are mounted in a folded, compact condition in conjunction with a gas generator, and upon sensing of a vehicle crash, the gas generator produces inflation gas which rapidly deploys and inflates the air bag.
The passenger side air bag is typically mounted in the dashboard and deploys toward the passenger as the passenger experiences relative motion toward the windshield, dashboard and deploying air bag. The thrust or main axis of deployment of the air bag is directly toward the passenger, and the material of the air bag initially forms an elongated column, the end of which may strike the driver, sometimes in the face, occasionally resulting in abrasions. Additionally, if the passenger's head is decelerated by the air bag while the passenger's torso is moving forward, the passenger can experience a whip lash motion. A further consideration is for small passengers and children who, if they do not impede against the air bag as it initially deploys, may slip under it and be less than fully protected.
The foregoing difficulties are exacerbated in vehicles mounting the air bag on an upwardly angled dashboard surface, whereby initial deployment is more upward than outward toward the passenger's torso.
Accordingly, one design objective for passenger side air bags is to limit the extent of outward deployment prior to full inflation and to encourage a vertically elongated frontal surface in early deployment of the passenger side air bag.
It is known in the prior art to provide air bags with internal tether straps to restrain the range of initial deployment toward the passenger. Two to four anchored tether straps or webs have their ends secured to the front panel of the air bag to limit the extent of deployment of the front panel toward the passenger. The tether strap system, although efficient in limiting the extent of deployment, has some drawbacks of its own. The tether straps add concentrated points of mass to the front panel, and this additional mass in part increases the likelihood of possible abrasions in that more kinetic energy is developed and imparted to the passenger if the air bag reaches the passenger. The tether straps also cause stress concentration at the attachment points, thereby requiring additional reinforcement to prevent failure of the air bag. Further, the tether straps add bulk and weight to the air bag module when it is desirable to keep the module as light in compact as possible for mounting in the dash. The tether strap system also has little effect upon the direction of deployment of the air bag, and encourages formation of a vertically elongated front only after outward deployment to the extent of the tether straps has occurred.
Accordingly, there is need for better control in the deployment of a passenger's side air bag while retaining simplicity and reliability in the manufacturing and operation thereof.